Hydraulic cement composition and method of making



gun-9e Patented Apr. 18, 1950 UNITED STATES PATENT OFF CE EXAMINILKHYDRAULIC CEMENT COMPOSITION AND METHOD OF MAKING John Perl, LosAngeles, Calif.

N Drawing. Application August 30, 1943, Serial No. 500,555

Claims. (Cl. 10693) This invention relates to compositions of matter forthe manufacture of building blocks. sheets, board and the likecomprising principally mineral hydraulic binders as represented byPortland filaments in which are included wood fiber such as sawdust,straw, reeds, rice hulls, nut shells and other plant fibers containingcellulose. The invention also relates to the process or making suchbuilding materials.

A general object of the invention is to combine cellulosic materialswith hydraulic binders to produce stone-like products which will possesslight weight and high insulation value, and will be capable of being cutwith saws and nailed with ordinary nails without cracking. But a" moreimportant object is to produce such li no-cement or othercement-cellulose products which will have high volume stability orresistance to expansion and contraction upon alternate wetting anddrying, and will not show disintegration tendencies subsequent to normalsetting.

Heretofore, when cellulosic materials have been combined in hydrauliccement compositions, they remove slstanges which lnterfer e w ith thesetting mgpertiesnfihecefiientfhut. althblTgfiretardation of setting ofthe cement has been thus avoided, nevertheless the resultant sodacellulose formed by reaction of the sodium hydroxide With the cellulosehas possessed the objectionable properties of causing disintegration toset in after the cement products have set normally and oi. impartingpoor volume stability to the cellulose cement products in that they havechanged dimensions greatly upon wetting and drying due to consequentexpansion and contraction respectively. This appears to be due to thefact that the-soda cellulose, which is water-soluble at leastin part,hydrolyzes or regenerates at least partially in the presence of thewater in the setting cement to produce amorphous cellulose. called"regenerated cellulose, which in turn is acted upon by liberated orregenerated sodium hydroxide and calcium hydroxide or the like in thecement to produce more regeneratable cel lulose" which likewise isregenerated or hy- -:irolyzed by water. The term regeneratablecellulose" is here applied to the alkali or soda cellulose because ofits regeneration to the amorphous regenerated" cellulose in the presenceof water. This regenerated cellulose I have found to cause setligno-cement or other set cellulose-cement product to expand when wettedwith water and to contract when drying takes place. This is a seriousobjection in building materials. The regenerated cellulose" alsoproduces the equally objectionable efiect of causing the set product todeteriorate or disintegrate slowly after normal setting has occurred.The terms soda cellulose," regenerated cellulose" and regeneratablecellulose, above defined as used in the present case, also are wellunderstood in the cellulose treating arts. The phenomena involved are: ell ulose which may be represented by the formifla CsHroOs): reacts withsodium hydroxide (NaOH) to'iorm soda cellulose represented'by theformula: CFHmOEANaOHT This is the regenerthe same compositionTfth"'original cellulose. While the compounds are thesaniebhmically,they are vastly different physically, in that the regenerated celluloseis amorphous in strucwill be noted that the regenerated cellulose hasture, whereas the originaliatiiralfiellulose is commonly classified asof crystalline structure/ Also, it is known in the art of viscose-silkmanufacture (an artificial silk or "regenerated" cellulose type), that aregenerated cellulose has an aflinity to condense with caustic sodathree times greater than the original crystalline cellulose. While thistheory appears to explain the phenoinena here encountered, I do not wishto be necessarily bound thereby since the true explanation might beotherwise. In any event, the "regenerated cellulose as the term is heredefined is objectionable for the reasons above stated. Potassi'umhydroxide produces the equally objectionable pgigslr cellulose, anotheralkali cellulose. MNMM I have discovered that cellulose materials cannew hick V treating saw g ded, such as sus ances found in sawdust, m thesame time avoiding the formation of objectionable alkali cellulose orregeneratable cellulose so that no regenerated cellulose" will form. Inother words, the treatedgellulosic ma; Ae ial. W111 ...ireemmsqq remzeggihjlgse or other regeneratable cellulose, and no "regenerated" oramorphous cellulose will form in the setting product to cause theobjectionable expansion, contraction and subsequent disintegrationmentioned.

These desirable results are preferably obtained by treating the sawdust,or other cellulosic material containing substances which retard thesetting of the cement, with ammonia gas or ammo: nium hydroxidesolution. These reactantsdo Hot'haye 'thbbjection'able type of causticOH group which is found in sodium and potassium hydroxides and thereforedo not form the objectionable regeneratable cellulose.

Briefly stated, the invention broadly resides in or similar cellulosicmaterial w imreaents which do not produce alkali cellulose or ot erregeneratable cellulose but nevertheless are capable of removingsubstantially all substances from the sawdust or kindred material whichwould interfere with the setting properties of hydraulic cement andwould retard its setting. Otherwise stated, the invention resides alsoin cellulosic materials and in semencelluloseprod'fitsiuch"as"ligno-cellulose"fire pared'from'sawdust andhydrauliccement, where the cellulosic materials have been treated tofree them from substances which would r tard the setting of the lcement, 'the treated cellulosic materials at the same time being freefrom the described regeneratable or alkali celluloses and regeneratedcelluloses. In a preferred aspect the invention includes such materialsand products where the cellulosic materials have been prepared bytreatment with ammonia gas or vapors or ammonium hydroxide solution.

Cement products which have been made with sawdust treated as hereinindicated have exhibited no observable expansion and contraction uponalternate wetting and drying, whereas building board made with Portlandcement and sawdust treated with caustic soda solution have exhibitedcharacteristically expansion of as much as one-sixteenth inch per linealfoot. Again, products made with sawdust according to the presentinvention have shown no tendency toward disintegration even after aboutthree years; whereas corresponding products made with causticsoda-treated sawdust have shown a decline in strength within a few weeksafter setting, and definite disintegration was in evidence within six oreight months.

Practice of the invention is relatively simple. Sawdust is the preferredcellulosic material because it is readily available in large quantities,is cheap, and is a good distender and insulating agent. Any apparatusfor soaking the sawdust in the solution used with subsequent washing maybe employed. Or if ammonia as is used, then a storage chamber mirequired together with a closed treating chamber in which the sawdust isplaced and into which the ammonia gas or vapors is introduced to thepoint of saturation of the sawdust, following which the e ammoniavapors. The

4 trega tedsawdust may then be either dried for subsequent useflir;mixed while still wet with Port; land cementfand other ingredien'tsTifdesired, in proportions to obtain a proper mix for forming 5 into shapesdesired and for subsequent setting.

When ammonia gas is employed, the sawdust usually naturally containssuflicient moisture for ammonia absorption to take place to an adequateextent. Otherwise steam may be introduced.

Saturation and extraction is allowed to take place for about 30 minutes,or for other appropriate time readily determined according to batchsize. The extract exudes from the sawdust and carries out substantiallyall the substances which would interfere with the subsequent setting ofthe cement with which the treated sawdust is mixed Subsequent steamingfollowed by washing removes the remainder of the extract and liberatesthe ammonia which is recovered for further washing. Where ammoniumhydroxide or other water solution is used, the sawdust is soaked in asolution of about 5% to about 15% concentration for about 30 minutes orother appropriate time determined for the size of the batch, whereuponthe solution is drained off and the sawdust washed with water.

One particular procedure employed in practicing the invention withsawdust and hydraulic cement is as follows: Gaseous or vaporousammoniagigpthe steaming (if-previously m onia extracted sawdust (or fromother sources) is by which the ammonia is absorb y the sawdust naturallyprovides sufficient moisture to combine with the ammonia vapors forproducing a liquid extract which exudes from the sawdust. Otherwisesuflicient steam may be introduced to supply the necessary moisture. The40 charge becomes completely saturated with ammonia and extract beginsto drain from the sawdust in about 30 minutes, or somewhat longeraccording to the size of the batch. When saturation is complete andextract drainage commences, the charge is then steamed to cause all ofthe extract to drain from the sawdust and to cause all of the ammonia tobe expelled from the sawdust. This may require an additional half hour,more or less according to the batch size. The ammonia vapors are led toa storage chamber for subsequent treatment of another batch of thecellulosic material.

When ammonia evolution ceases, the steamed batch is washed with water,preferably hot water, to remove all remaining extract. The wash watermay be treated with alkali or milk of lime to liberate ammonia presentwhich is returned to the cycle with previously liberated ammonia vapors.

These treatments remove all or substantially all of the substances inthe sawdust or other raw cellulosic material which would retard settingof the cement subsequently used in preparing the artificial stoneproduct. At the same time the described regeneratable celluloses are notformed.

, The wet, treated cellulose is now ready to be combined with hydrauliccement such as the ordinary Portland cement and such other mate- 70rials as may be desired. Enough cement is used to completely coat thetreated sawdust or other treated cellulosic material and enough water isadded to yield the desired consistency. To prepare the mixture forpressing into blocks only 7 enough water will be employed to yield amixture LAHHmu-H that would be termed moist." For casting, a slurry isused such that, when a quantity is squeezed in the hand, only a slightamount of water oozes to the surface. Where the indicated amount ofcement to coat the sawdust particles is used, a high insulating capacityis obtained by reason of the relatively large proportion of sawdust orother cellulose material.

Very desirable products possessing the properties heretofore stated,have been made from the following, both blocks and board having beenproduced therefrom:

Parts by Parts by Weight Volume Wet treated sawdust... 100 100 PortlandCement 300 about 50 Inert mineral fillers to 150 0 to C! Mineral fillersused may be diatomaceous earth, ground s t talc gr 51 10a our, umice ndthe iike, but ey may m omittfi. Also the proportion of cement may bevaried. Thus, as a general formula for the production of aligno-concrete from treated sawdust and Portland cement, the followingtable indicates desirable ranges of the materials used:

Parts by volume Treated wet sawdust 100 Portland cement to 200 Inertmineral filler Oto 85 As the cellulosic materials and the mineralfillers vary, those skilled in the art will readily understand thatproportions may be varied which would afiect the setting of hydrauliccemerit mixed therewith in the presence of water, which comprisescontacting the cellulosic material with ammonia gas in the presence 01'moisture to the point of saturation of the material and until extractexudes, washing out the extract andheating the material to expel theammonia vapors, separating the wet extracted cellulose, mixing the wetsawdust materials with hydraulic cement, and shaping the mixture.

3. A composition of matter containing between about 15 parts and about200 parts by volume of Portland cement and about parts by volume ofligneous cellulosic particles extracted with an aqueous solution ofammonia to remove substances soluble therein which would interfere withsetting of the cement, and washed with water to eliminate the extract.

4. A composition comprising ligneous cellulosic particles which havebeen extracted with an aqueous solution of ammonia to remove substancessoluble therein, and Portland cement suflicient to coat the extractedparticles and bind them together, but insuificient to completely fillthe voids between the particles.

5. A composition as in claim 3 wherein the extracted particles areextracted wood particles such as wood sawdust.

JOHN PERL.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 256,436 Kllmisch Apr. 11, 18821,016,178 Sammet Jan. 30, 1912 1,153,883 Arledter Sept. 21, 19151,259,502 Farr Mar. 19, 1919 1,471,975 Zukoski Oct. 23, 1923 1,802,715Hixon Apr. 28, 1931 FOREIGN PATENTS Number Country Date i, 5

155,268 Great Britain 1922 321,744 Great Britain 19291 396,652 GreatBritain 1933 ""13, 453,905 Great Britain 1936 476,999 Great Britain 1937

1. A COMPOSITION COMPRISING WOOD PARTICLES EXTRACTED WITH AMMONIA INSOLUTION IN WATER TO REMOVE AMMONIA-SOLUBLE SUBSTANCES, AND HYDRAULICCEMENT COATING SAID WOOD PARTICLES.